Proteases have conventionally been used in a variety of fields such as various detergents (including laundry detergents), cosmetics, bath agents, food modifiers, and pharmaceuticals (such as digestion aids and anti-inflammatory agents). Of these uses, proteases for detergents are industrially produced in the largest amount and have a great market value. Accordingly, a number of proteases are now available on the market.
In most cases, stains on clothes contain not only proteins but also plural components such as lipids and solid particles. Therefore, there is a demand for detergents having a sufficient detergency to remove complex stains. To address this demand, the present inventors applied for a patent (WO99/18218), which provided alkaline proteases having a molecular weight of about 43,000 that are capable of retaining caseinolytic activity even in the presence of a high concentration of fatty acids. The alkaline protease provided in WO99/18218 also exhibited excellent detergency even when the stain is composed of not a simple protein component but plural components, for example, protein and lipid.
Alkaline proteases having improved specific activity, oxidant resistance and detergency that are usable for detergents of wide-ranging compositions remain in demand.